Sheath/core bicomponent filaments and process of preparing same

ABSTRACT

SHEATH/CORE BICOMPONENT FILAMENTS HAVING A CORE DERIVED FROM A FIBRE-FORMING LINEAR POLYAMIDE OR COPOLYAMIDE AND A SHEATH DERIVED FROM A COPOLYESTER OR COPOLYAMIDE CONTAINING POLY (ALKYLENE OXIDE) RADICALS.

AVAILABLE COPY vniwdsw s s 679 541 SHEATH/CORE mcorrroNEN'r FILAMENTSAND PROCESS on PREPARING SAME, Anthony Charles Davis, Pontypool, and IanStuart Fisher,

Harrogate, England, assignors to Imperial Chemical Industries Limited,London, England I No Drawing. Filed July 20, 1970, Ser. No. 56,667

Claims priority, applicaigr; 1 Britain, July 28, 1969,

Int. Cl. D0111; 5/28 us. CI. 161- -175 I r a Claims ABSTRACT on THEDISCLOSURE,

This invention relates to bicomponentfilaments having soil-release,anti-soil redeposition and antistatic properties, these properties beingdurable throughout conventional textile processing and subsequent use.

Processes for improving the hydrophilic propertiesv of polyamide textilematerials are well known. For example, surface treatments by hydrophiliccoatings have been proposed; however, none of these have been entirelysatisfactory since they have either lacked durability or have adverselyaffected fabric handle.

Homofilaments comprising copolymers containing hydrophilic componentshave also been suggested. In most cases, the introduction ofthe'hydrophilic component has adversely alfec ted'the tensile propertiesor decreased the resistance to degradation by heat and light..

In yet another. priorart method, filaments have been produced frompolyamide polymers having hydrophilic additives dispersed therein. Thehydrophilic properties of such filaments, although good initially;deteriorate with treatments such as repeated washing due to leaching outofthe additive. v T I ,We now provide a process by means of whichfilaments may be produced having adequate tensile properties andresistance to degradation for all normal fibre uses and at the same timehaving good antistatic and soil-release properties which remainthroughout conventional textile processing treatments and subsequent useincluding repeated washing and cleaning treatments. M

According to the present invention we provide a process for thepreparation of a bicomponent filament by the extrusion of two streams ofdifferent molten polymers in sheath/core relationship, the core beingderived from a fibre iforming linear polyamide or copolyamide and the.sheathbeing derived essentiallyfrom a-copolyesteror copolyamidecontaining poly (alkylene oxide) radicals in an amount such as wouldresult from the reaction of not less than 5 parts by weight of poly(alkylene oxide) per 100 parts by" weight of the'final'copolyester orcopolyamide, allowing the conjugate stream to solidify to form afilament and subsequently drawing. Our invention also in- Q I latentedJuly 25, 1972 Examples of simple glycols are those of the form HO(CH OH,wherein n is not less than 2 and not greater than 10, and 1:4-bis(hydroxymethyl) cyclohexane. In the term simple glycol we also includemore than one simple glycol.

Examples of suitable dicarboxylic acids on which the copolyesters of thesheat may be based are terephthalic, naphthalene-2:o-dicarboxylic andl':2 -diphenoxyethane- 4:4'-dicarboxylic acids. We also include the useof more than one dicarboxylic acid. Suitable second dicarboxylic acidsare, for example, adipic, isophthalic and sulphoisophthalic acids. Thepoly (alkylene oxide) should preferably be poly (ethylene oxide) or poly(propylene oxide), having an average molecular weight not less than1,000 and not greater than 20,000. Preferably the average molecularweight should be not greater than 6,000. The average molecular weight inquestion is that for distribution of molecular weight of poly (alkyleneoxide) as manufactured. It is convenient and preferred to use a poly(alkylene oxide) glycol in the preparation of the copolyester.

When the sheath is a copolyester, it is most practicable to use acopolyester of ethylene terephthalate and poly (oxyethylene)terephthalate.

Copolyamides suitable for the sheath component are based, on aliphatica,w-dicarboxylic acid and a poly (alkylene oxide) diamine with analiphatic a,w-diamine or an aliphatic w-amino-carboxylic acid or withboth.

Examples of aliphatic dicarboxylic acids on which the sheath may bebased are adipic acid, pimelic acid and sebacic acid.

Examples of suitable aliphatic diamines are those of the form H 'N(CH),,NH wherein n is not less than 4 and not greater than 10.

The amino-carboxylic acid may be in the form of its l-act-am such as,for example, epsilon-caprolactam.

The proportion of structural units of the sheath component which arederived from poly (alkylene oxide) should not exceed that which wouldresult from the reaction of 60 parts, preferably 40 parts, by weight ofpoly (alkylene oxide) in the formation of parts by weight of the finalcopolyester or copolyamide.

.In order to avoid spun yarn stickiness, which leads to difiiculty inunwinding packages of spun yarn during drawing, it is preferable thatthe proportion of structural units of the sheath component which arederived from poly (alkylene oxide) is not excessive. This proportion maybe greater in the case of a higher molecular weight poly (alkyleneoxide) than in the case of a lower molecular weight poly (alkyleneoxide).

We have found particularly advantageous the use of sheath component of acopolyester or copolyamide which is fibre-forming and which has anefiective melting point not less than 200 C. These conditions favorsuccessful extrusion to form filaments and successful orientation bycold drawing.

v The proportion of the conjugate filament cross-section which iscomposed of the sheath component should be sutlicient such that thesheath comprises a major proportion of the filament surface. It mayprovide an entire sheath about the core, on the other hand suchproportions should not be so great that the dye-fastness and lightresistance properties are adversely affected. After subjecting thesheath/ core filaments of our invention to a dyeing procedure, theresultant filaments may be reduction cleared, according to knowntechniques. This treatment results in removal of the dyestutf from thesheath of the filaments so that the lack of dye-fastness and the lack oflight resistance normally associated with the presence of dyestuff inthe material of which the sheath is composed is no longer a problem. Onthe other hand, the presence of dyestulf in the core of the filamentsensures the desirable coloured gfiltflam coin pea ance o the fi am n mid th as ut in. t e. sets section. Any convenient method maybe used forthe formation of the sheath/core filaments of thepresent invention, J AThe filaments manufactured according to the process of our invention maybe produced by the use of a multi-hole spinneret toform a yarn. whichmay be oriented by colddrawing according to methods known in the art.

g The sheath" and core may optionally contain additives commonlypresent, and in the amounts commonly used to produce, desired effects,for example colouring materials; delustrants, 'dyeing'additives andstabilizers. Such effects may be confined to the sheath or to the core.I k The filaments of our invention may be used in all tex-- tile uses,as continuous filament or staple fibre alone or in admixture with otherfilaments or fibres particularlywhere soil redeposition, antisoiling andantistatic vproperties are important.

, EXAMPLE 1 f A core/sheath bicomponent yarn was melt-spun at 27 5 C.from a laboratory twin barrel hydraulic extruderl The core polymer'was6.6 nylon containing 0.3% TiO and having a relative viscosity of 37 andthe sheath mer was a copolyester formed from a mixture of equal weightsof poly '(oxyethylene) glycols of 4000 6000 mol. wt. (19% by wt. ofcopolyester), ethylene glycol, and

terephthalic acid, containing 0.5% TiO, and having an inherent viscosityof r68and containing as antioxidants 0.09% of2,4-dimethyl-6-methylcyclohexylphenol, 0.09 of triphenyl phosphite. AS-filament yarn in 'whichthe core occupied 40% of the cross-sectionalarea was wound up'at 400 'ftJinin. and subsequently drawn toa'ratio of:1 usinga' snubber pin at 70 C. and a hot-plate at 175? C. The drawnyarn had a denier of 37.3, tenacity 2.5 g./ denier and extensibility11.6%. A control'S-fiIanient yarn spun at 275 C. from the nylon polymeronly and drawnunder the same conditions had a denierf of 35l0; bi.detftiiei'ffv 201, havi ng a f .7 .gJdenienand an tenacity 5.3gJ/denierand extensibility 20.1%. Each drawn yarn was four-folded and convertedto a weft-knitted fabric sample. The fabrics were washedltn removespinning finish and tested as follows: p (a) Samples of fabric'wererinsed in 0.15% aqueous potassium bromide solution and-dried; and theelectrical resistance of a square of the fabric was measured afterconditioning to a relative humidity of 65. Results were as I follows:bicomponent fabric-8X10" ohms; nylon control fabric-above 10 ohms. Y

(b) Samples of fabricwere impregnated with %of their weight of dibutylphthalate and given washing treatments of different intensity. Thepercentage-of-theoriginal oilapplied remaining on the fabric sample wereas follows:

Percent oil retained after- 6'min.in' 7' l 2hrs..ln 0.07% 1'hr.'in 0.07%0.07% aqueous aqueous aqueous commercial commercial m soap detergentsoap solution solution Sample at 60 C. at 60C. at 60 Q.

Bicomponent-l'abric 12.0 10.9 i 1o.'2 Nylon control fabric 52. 5 29. VEXAMPLEZ I, f

' A525 denier yarn consisting of 40 core/sheath bi' component filamentswas spun and wound up'at 1718-fill min.-using the apparatus described inBritish patent cification No. l,100,430. The volume ratio of-co re tosheath was 80/20. The "core component awas 6.6' nylon :centricconformation and of circular or non-circular crosshate w s econtalnmg0.3% TiO,

Example 1. The yarn was cold-drawn to'a ratio of 3.21 giving an orientedyarn of'i'denier 209 with a tenacity of 3.3 gJdenier and extensibility41%. A control yarn was spun from a standard nylon .melt-spinning unitat 1718 ftJmim, using the. same ny1on polymen: and ::dr;awn toa ratio of3.21to an oriented yarn of denier 208, tenacity 3.75 g./denier andextensibility 47%. Each yarn was 'converted to woven-fabric and thefabrics were scoured in a detergent/sodium carbonate I solution at, C.One portionof ach fabric was rinsed in distilled -water*andf'" other in0. 15 %-p otassiiim bromidesolutioiii Both fabrics were dried andconditionedin air of known relative humidity, and the fabric electricalresistance was .measured; with the' fabric sample resting on aninsulating" sheet, the DC. resistance was "measuredbetween concentriccircular metaltelectrodes,resting on the upper surface of the fabric andof such dimensions that theannular gap had an inner diameter of50.'8'mmla d an outer diameterof 58.8 mm; Results were asfollowsi HBicomponent yarn Control nylon yarn Water I KBr Water KBr rlnse H rinserinse v r 1 rinse 6X10 5x16 4.6X10 1.2xi6 'i polyether glycols wasincreased to 25% of the total weight e ac ete- 11 We a .d weare 's bbstpin .at.90? C..to a ratio of. 3 .49 t gi an oriented yarn extensibilityof 56%. A'con tr'ol' 'y'arn was spun and. ewn. m the ny a o a eonly. withcj'same pm es' f n i ic siti a drewnyau c' 1 d ie h s a' tenacity of4.4.Yg./,de nier and aii e xtensibilit y of. 60%. The two yarns werescpately converted to woven r s wh h .iwq e e a e ec r c esi n emeasurement by scouring and .rinsingas in Example ,2,

The tendency of the scoured fabrics to, cling due to electro:

static charge was, assessed comparatively by. frictional.electrification against (ethylene terephthalate) fabric; the electrifiedsampleswere allowed to cling to an earthe'd metal plate at 7O It'o.thehorizontal and the timefor which clinging continued was measured."Measurements were m d We. new 3' and having relative viscosity of.42.,.and..the. heat po ymer. w s.. hecppqlmtetusciiu R.H. of 38%.

BET AVAILABLE COPY orders (depending on .the ionic content of theyarn,ples) below that of controlnylonyarmand to have no fiction No.1,100,430. Thevolume ratio of core to sheath was 80/20. The corecomponent was 6.6 nylon containing 0.2% TiO, and' having a relativeviscosity of 45, and

-the sheath co'mponent was the-copolyester used in'Example l." Thespun'yarn was two-folded and drawn and ci-imped in one operation, givinga bulky yarn containing l38 filaments havinga denier of 2334,tenacity'2.34

'gJdenier and extensibility 41%. The yarn was used 'to construct a looppilecarpet bytufting into a hessian backing. An adjoining section. ofcarpet was tufted with a standard crimped carpet 'yarn of the same'nylon polymer 1 of 2450 denier. Separate lengthsof carpet eachincorporating both types of yarn were finished (a) by. adetergent/sodium carbonate scour and water rinse, and (b) by dyeing withDuranol blue BN 300 (1% on weight of carpet).

The carpet pieces after drying were given a secondary bessian backingwith a latex adhesive and their electrical properties were assessedunder defined humidity conditions by resistance testing and staticcharge generation measurement. Electrical resistance was measured as inExample 2. Static charging propensity was assessed by measuring the bodyvoltage acquired by a person walking on the carpets with shoe soles ofeither leather or a composition material, and the time for the voltageto decay to half its value was recorded. Results were as iz'or thecopolyamide. Each yarn was cold-drawn to a ratio-=ofr. 4.0, givingoriented yarns with the following physical properties:

Tenacity Extensibility p I Denier (gJdenier) (percent) Bicomponent yarns26. 8 3. 5 43. 8 copolyamide yarn 35. 9 3. 2 39. 2 Nylon 6.6 yarn 35. 95. 2 69. 6

Each' yarnwas knitted into a hose-leg panel, which "measured afterconditioning was scoured in detergent/sodium carbonate solution toremove spinning finish. Tests to determine the electrical andhydrophilic properties were made as follows:

* (a) The electrical resistance of a square of fabric was in anatmosphere of relativeihumidity 31 or 60. *(b) *Squares of fabric wereelectrified by friction against talc and allowedjto cling against avertical electrically'e'arthed metal surface in an atmosphere atrelative humidity-30. The time until the'sample dropped away wasmeasured.

E (excellent)--oil collects into drops which float off the fabric inunder one minute VG (very good)oil droplets released slowly during 5minutes G (good)oil collects into droplets which cling to the follows:fabric Carpet resistance (ohms) Static charge in walking at 40% RH.

Maximum voltage (kv.) Decay time (see) Composi- Leather Composi- LeatherYarn type R.H. 65% RH. 40% tion sole sole tion sole sole Bi-comorient..." 6. 1X10 11 2Xl0 3 1.5 20 20 Contzo nylon 1. 1X10 2X10 4 2.525 30 The results showed that the electrical resistance of thebicomponent filament carpet was less than that of a normal nylon carpet,and that static charges generated were smaller and decayed more rapidly,thus lessening the risk of an unpleasant electric shock.

EXAMPLE 5 A S-filament core/sheath bicomponent yarn was melt- M(moderate)-oily area contracts but does not all collect into droplets P(poor)oily areas unchanged or widening.

Fabrics were tested for oil-release properties in the scoured state andafter 1 hour or 3 hours of washing in 0.4% Persil at C.

Test results are shown in the following table.

Electrical resistance Hydrophilie properties (ohms) Duration-- of clingWashed Washed 60%R.H. 31% RH. (sec.) Secured 1hr. 3hrs.

Bicomponent yarn 2.5Xl0 7.0X10 81 VG G-VG G-VG copolyamide yarn 2.9Xl07.0Xl0 115 VG- VG G-VG Nylon6.6.yarn 6.5)(10 1.0)(10 300 M P P spun at310 C. using the apparatus of Example 1 and wound up at 400 ft./min. Thecore polymer was 6.6 nylon containing no additives and having a relativeviscosity of 45. The sheath polymer was a copolyamide prepared fromhexamethylenediamine, adipic acid and a diamine prepared frompolyoxyethylene glycol of molecular weight 1540 by reaction with thiorylchloride followed by ammonia, substantially as described in Britishpatent specification No. 948,507. The weight proportion of the polyetherdiamine in the copolyamide was 15%, and the sheath occupied 40% of thecross-sectional area. Control 5-filament yarns were spun using asingle-barrel extruder from the separate polymers alone, with a melttemperature of 3. A sheath/core bicomponent filament according to 292 C.for the 6.6 nylon homopolymer and 290 C. claim 1 in which the poly(alkylene oxide) is poly (ethylene oxide) having an avgfage molecular.weight in the 'nge'-1,000"t020;000 inclusive. f 1* 4; LA: sheatlilcorerrbicpmponent 'filament-"l'aiccordin'g :to claim 1 in which thecopolyester of lthejhe'at hcontains ;b ;.;w s t q P971)! (alisylysmsisle). 2st 09. art e y dieifilit of the;,;s a id copolyester. I a";1,5. A sheath/core bicqmponent filament aeeordingfto vizlaimd in'which.zthe Sheathecomprises oascopolyesterof .my

I oxlqe) per 100 ggrtshy veight of sgigleopplyester.

iziEld Boil NEH, Pmnar time;

component occupies no leg; than 5% and no greater than 33%offlthecross-sectional area-of the filament: 1 1+ 8; :A process according-toc1aimi6- in which the copoly- =estenfof thesheatheontains poly(alkyleneroxide-yradiczils in an amount such as would result from,tliereactionzof not more than 40 paitsfby wweight of poly (alkyleneLlhlK ERg lm, Examiner I f U.S.'Cl. X.R.e V

